Transmitter.



J. J. COMER.

TRANSMITTER.

APPLICATION FILED MAR.31,1913.

Patented Mar. 14,1916.

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Specification of Letters Patent.

Patented Mar. is, rare.

t Application filerl March 31, 1913. Ser1a1No. 758,0be.

To all whom it may concern:

Be it known that 1, JOHN J. Comma, a citizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Transmitters of which the following is a specification.

My invention relates to improvements in transmitters, and more particularly to transmitters comprising a granular resist 'ance medium employed to transmit voice and musical vibrations. In transmitters of I this typein which a granular resistance medium is employed, it has been found that the range of the amplitude of the vibrations to which the granular material can be subjected is very small. If the vibrations are too minute, of course the granular material is not affected sufficiently so as to give any operative results, whlle if the vibrations are too great the circuit is broken between the individual granules of material, thus producing a very harsh and unnatural effect. In order to maintain the vibrations within this narrow range between which thebest results are obtained, recoursehas heretofore been had to the method of damping the diaphragm, for example, to which the transmitter is secured. Such a method, however, has been found to be unsatisfactory, as in order to obtainthe most accurate results the diaphragm or other vibrating member from which the transmitter receives its vibrations should be allowed perfectly free vibration. When the diaphragm is damped, it has the result of blotting out certain of the over-tones, thus rendering transmission imperfect.

The object of my invention is to bring the vibrations which affect the granular material into the proper range by means entirely independent of the diaphragm or vi brating member, whereby the diaphragm is left free to vibrate and is not impeded or damped. The means for controlling the vibration reside in the transmitter button itself, the vibrations being .so controlled that very efficient results are obtained.

My invention is particularly adapted for use in musical transmission, whereby very delicate adjustments are required.

rectly with the soundingboard or vibrating member of amusical instrument, such as a piano or VIOlln.

My invention will be more readily un- F ig. :2- is a sectional View taken on the line 2-2 in Fig. 1. Fig. 3 is a view partly in section, showing my invention 'as applied to a diaphragm in ordinary telephone work. Fig. 4 is a View showing my invention as applied to the sounding-board of a piano.

As illustrated, my transmittercomprises an inclosed casing. comprising the opposing cup-shaped members 6 and 7, which are circular in form and provided with upwardly extending portions 8 and 9-, which are formed so as to provide an opening 10 for filling the receptacle. Passing through the center of the members ,6 and 7, which form the inclosing casing, is the stem 11 which carries the movable electrode 12. Stationary electrodes 13 and 14: are mounted on opposite sitles of the casing, being carried by the disks 15 and 16, respectively,

portion,

Sur-

washers are insulated from. the casing.-

Likewise, mounted upon each flange is a hollow cone-shaped member 19 lined with a felt member 20 with which an adjustable cone 21, carried by the stem 11, is adapted to engage. This cone 21 is adjustable along the stem 11 by means of the nut 22 which is threaded upon the stem 11, so that by advancing the nut, the cone 21 is pressed against the felt member 20.

As illustrated, the transmitter is the same on both sides of the casing, so that by tightening upon the nuts 22 the pressure on the felt member 20 can be increased. The casing is filled with granular resistance material, such as granular carbon and fluffy asbestos placed around the stem 11 to pre vent short circuiting, and the hole 10, by

which the transmitter -is filled, is likewise packed with flufiy asbestos. The sides of the casing are insulated to prevent the casing itself from short circuiting the resistance material.

The transmitter as described can be at- Inoperation', assume that the device is applied as shown in Fig.3, the diaphragm 23 receives the sound vibrations, and being undamped is free to vibrate. In orderto properly control the vibrations so that they will come Within the range through which the carbon material operates most efficiently, it is merely necessary to properly adjust the position of the ,cones 21, so as to regulate the pressure upon the felt pads or member 20. It will be seen that as illustrated the transmitter is of the inertia type-that is, the entire transmitter is moved by the vibration of the diaphragm. If the cones 21 are adjusted so that the pressure on the felt pads 20 isincreased to such an extent that there is practically a solid connection between the stem 11 and the transmitter casing, thevibrations of thediaphragm will have practically'no effect upon the granular materiall As the nuts22 are loosened, however, so asto decrease the pressure upon the felt pads 20, there will be a slight play or movement between the stem 11 and the easing, thus causing a slight movement of the electrode 12, which is carried by the stem, with respect to the electrodes 13 and 14: carried by the casing. In this manner, by properlyregulating the tension on the felt pads 20, a very accurate adjustment can be obtained, in a very simple manner.

I find that by the use of this device I am able to bring very lar e vibrations down to the range at which t 1e granular material will be most efliciently operated. Heretoforegreat difficulty has been experienced 'in taking vibrations directly 01f of musical instruments, due to the amplitude of the vibrations so received. This is especially true of the piano, in which the vibrations are particularly heavy. I find that I can obtain very efficient results in this manner by the use of my improved transmitter.

While I have illustrated and described one particular embodiment of my invention, and have illustrated my invention particularly in connection with a double transmitter, it is. of course, to be understood that I do not trode with respect to said casing.

resistance material within ried by. said stem, a vibrating member free to vibrate secured to said stem, to thereby vibrate said stem, electrode and casing, and means independent of said member for damping the vibrations of said respect to said electrode.

2. In a transmitter, a granular resistance receptacle, a stem carrying an electrode associated with said receptacle, a member adapted to be vibrated to which said'stem is secured, whereby a vibration of said member vibrates said electrode and receptacle, and adjustable means for damping the amount of vibration of said electrode with respect to said casing.

3. In a transmitter, astem, secured to said stem, a casing carried by said stem and loosely mounted thereon, and means for adjustmg the connection between said stem andcasing, wherebythe relative casing with o a diaphragm vibrations between said stem and easing can:

be regulated.

4. In a transmitter, a stem, a diaphragm-4 secured thereto, a casing loosely mounted on said stem, anelectrode rigidly mounted on said stem, whereby when said diaphra is vibrated said electrode is moved relative to said casing, and means for adjusting the connectionbetween said stem and casing to thereby regulate the movement of said elec- 5. In a transmitter, a casing, granular said casing, a stem passing through said casing, a diaphragm carried bysaid stem, means for vibrating said stem,.connections between said stemand casing whereby the vibrations of said stem are imparted to said. casing, and

means for adjusting said connections to thereby regulate the amount of movement of said stem and electrode with respect to said casing.

6. In a transmitter, a casing containing granular resistance material, a stem passing 7 through said casing, an electrode within said casing and carried by said stem, and flexible connections between said stem and said casing whereby said stem and electrode are adapted to move relative to said casing.

7. In a transmitter, a casing containing granular resistance material, a stem passing through said casing, an electrode within said casing and carried by said stem, flexible connections between said stem and said casing whereby said stem and electrode are adapted to move relative to said casing, and means for adjusting said flexible connections timers to thereby regulate the movement of said stem and electrodes with respect to said casing.

8.111 a transmitter, a casing, granular resistance material in said casing, a stem passing through said casing, an electrode carried on said stem, a diaphragm secured to said stem whereby the vibration of said diaphragm is imparted to said stem and easing, an engaging member carried by said stem, a co-acting member on said casing, and a resilient niediiun between said member whereby the vibrations of said electrode with respect to said casing are damped 9. In a transmitter, a casing, granular resistance material within said casing, a stem passing through casing, an electrode in said casing carried by said stein, a hollow cone-shaped member on said casing surrounding said stem, and provided with a felt face, a beveled member on said stem adapted to engage said felt, and a diaphragm secured to said stem, whereby the vibrations ofrsaid diaphragm are imparted to said stem and easing", the felt connection permitting movement of said stem with respect to said casing.

10. In a transmitter, a casing, granular resistance material within said casing, a stem passing tl'irough said casing, an electrode in said casing carried by said stem, a hollow CUIlG-SAZIPGd member on said casing surrounding said stem, and provided with a felt face, a beveled member on said' stem adapted to engage said. felt, a diaphragm secured to said stem, whereby the vibrations of said diaphragmare imparted to said stem and easing, the felt connection permitling movement of said stem with respect to said casing, and means for adjusting said beveled member on said stem to thereby regulate the pressure on said felt, whereby the vibrations of said electrode with respect to said casing are adjustable.

11. In a transn'iitter, a casing, a pair of electrodes on the opposite sides of said casing, a third electrode located between the first n'ientioned electrodes, granular resistance material between said electrodes, a stem passing through said box and. carrying said third electrode, and resilient connections between said stem and said casing, whereby a limited movement of said third electrode with respect to said other electrode is permitted.

12. In a transmitter, a casing, a pair of electrodes on the opposite sides of said casing, a third electrode located between the first mentioned electrodes, granular resistance material between said electrodes, a stem passing through said box and carryingsaid third electrode, resilient connections betweensaid stem and said casing, whereby a limited movement of said third electrode with respect to said other electrode is permitted, and means for adjusting said flexible connections to regulate the movement between electrodes,

13. In a transmitter, a casing, electrodes mounted on the opposite sides of said casing, a thiri'l electrode between said first mentioned electrodes, granular resistance material in said box and surrounding said third electrode, a stem passing through said casing on which said third electrode is mounted, and flexible connections on opposite sides of said casing to said stem, whereby a limited movement of said stem with respect to said casing is permitted.

14:. In a transmitter, a casing, electrodes mounted on the opposite sides of said casing, a third electrode between said first mentioned electrodes, granular resistance material in said box and surrounding said third electrode, a stem passing through said casing on which said third electrode is mounted, flexible connections on opposite sides of said casing to said stem, whereby a limited movement of said stem with respect to said casing is permitted, and means for adjusting said flexible connections to thereby regulate the amount of mc vei'nent permitted between said third electrode and said casing.

Signed by me at Chicago, Illinois, this 22nd day cl: March, 1913.

JOHN J. COMER.

"Witnesses: .7. Norm, E. H. Canoe. 

